Birthday girl Angelique Kerber unwraps perfect present at Australian Open

World No 1 Angelique Kerber made it to the Australian Open third round, but she had to work hard against fellow German Carina Witthoeft.The defending champion, who turned 29, battled through 6-2, 6-7 (3/7), 6-2 and will next face Czech Kristyna Pliskova, sister of fifth seed Karolina Pliskova.

It was an aberration with the birthday girl immediately breaking back, before turning up the heat as they traded blows to score another break when Witthoeft whipped a forehand long to go 2-5 down, with Kerber easily holding to take the set.

Bidding to be the first woman to defend her Australian title since Victoria Azarenka in 2013, Kerber had an indifferent lead-up to Melbourne with early exits in Brisbane and Sydney this month.

She has slowly been improving as he works her way deeper into the Australian Open and towards a potential quarter-final against Garbine Muguruza, with Williams seeded to meet her in the final.

She came out firing in the second set, ambushing Witthoeft for an early 2-0 lead. But she lost focus and her countrywoman made the most of it, breaking back with some pinpoint shots from the baseline.

The set turned into a slug-fest and Kerber succumbed to the pressure in the tiebreak, firing blanks on her serve which allowed Witthoeft to win six points in row and take the set.

Kerber was rattled and lost her opening service game to love, but she quickly regrouped as the crowd got behind her to break back.

A tired Witthoeft had no response and her previously stern resistance crumbled into surrender.